The invention relates to fuser control, in particular, to a system of fuser temperature control as a function of copy sheet characteristics.
Reproduction machines such as copiers and printers continue to have increasing demands on the variety of jobs to be accomplished. One such demand is to be able to manipulate copy sheets of varying characteristics such as size, weight, and material. In addition, there is often the need to alter the orientation of the copy sheets throughout the copy sheet path. One element of a printer or reproduction machine that is often stressed by varying copy sheets is the fuser element. A fuser roll can easily be subjected to significant temperature variations along its axis by copy sheets of different characteristics. For example, a copy sheet of a width significantly shorter than the heating element used for a more standard size copy sheet, will cause a substantial differential of temperature across the fuser roll. This will cause premature stress and deterioration of the fuser roll.
A possible solution is the use of multiple heating elements. A difficulty with multiple heating elements is the cost as well as the problem of selecting heating elements that conform to the variety of copy sheets available at various sizes. In the prior art, U.S. Pat. No. 4,372,675 discloses a method for adjusting fuser operation in response to variable available power. In particular, with less than full power available to the machine, the fuser is operated at less than full power. Upon detecting that the fuser temperature has fallen below a threshold level, the machine is set in standby and full power is applied to the fuser to return the fuser temperature to an acceptable level to continue operation. This system, however, is not concerned with the deterioration of a fuser roll by fusing copy sheets of variable characteristics.
It would be desirable, therefore, to overcome the limitations of the prior art in avoiding wear and tear on fuser rolls caused by fusing non uniform copy sheets. An object of the present invention, therefore, is to provide a technique to evade unnecessary component deterioration on a fuser roll required to receive copy sheets of varying characteristics. Another object of the present invention is to be able to adjust the operation of a fuser heating element in response to copy sheet characteristics such as size, weight, material, and orientation. Further advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.